PHPExcel生成Excel文件---提示导出文件或者文件扩展名不一致，或导出的文件或文件扩展名无效

$data = Db::name('shop_cart')->where('phone','15555555555')->select();
        $objPHPExcel = new PHPExcel();//实例化PHPExcel类 等同于在桌面上新建一个Excel表格
        $objSheet = $objPHPExcel->getActiveSheet();//获得当前活动sheet的操作对象
        $objSheet->setTitle('demo');//给当前活动sheet设置名字
        $objSheet->setCellValue("A1","序号")->setCellValue("B1","产品编号");
        $objSheet->setCellValue("C1","产品名称")->setCellValue("D1","产品规格");
        $objSheet->setCellValue("E1","浓度")->setCellValue("F1","原价");
        $objSheet->setCellValue("G1","优惠价")->setCellValue("H1","货期");
        $objSheet->setCellValue("I1","有效期")->setCellValue("J1","批次号");
        $objSheet->setCellValue("K1","供货商")->setCellValue("L1","数量");
        $objSheet->setCellValue("M1","金额")->setCellValue("N1","备注");
        $j = 2;
        foreach($data as $key => $val){
            if($val['good_stock'] > 50){
                $val['good_stock'] = '有货';
            }else if($val['good_stock'] < 50 && $val['good_stock'] > 50){
                $val['good_stock'] = '缺货';
            }else{
                $val['good_stock'] = '暂无';
            }
            $val['good_indate'] = date('Y-m-d',$val['good_indate']);
            $objSheet->setCellValue("A".$j,$key+1)->setCellValue("B".$j,$val['good_num'])->setCellValue("C".$j,$val['good_name'])->setCellValue("D".$j,$val['good_spe'])->setCellValue("E".$j,$val['good_standard'])->setCellValue("F".$j,$val['normal_price'])->setCellValue("G".$j,$val['member_price'])->setCellValue("H".$j,$val['good_stock'])->setCellValue("I".$j,$val['good_indate'])->setCellValue("J".$j,$val['good_batch'])->setCellValue("K".$j,$val['company'])->setCellValue("L".$j,$val['good_count'])->setCellValue("M".$j,$val['good_subtotal'])->setCellValue("N".$j,'');
            $j++;
        }
        ob_end_clean();//清除缓冲区,避免乱码
        header('Content-Type: application/vnd.ms-excel');
        header('Content-Disposition: attachment;filename="links_out.xls"');
        header('Cache-Control: max-age=0');
        $objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, 'Excel5');
        $objWriter->save('php://output');

　　之前怎么做下载下来的文件都是错误格式的。本来就对Excel文件不熟悉，不怎么用，结果就在2003跟2007之间晕了，其实写的没错，

只是没有清除缓冲区
ob_end_clean();

，所以才会提示导出文件或者文件扩展名不一致，或导出的文件或文件扩展名无效，现在Excel5是没问题了，但是Excel2007还是不成功，还需要继续调整